Мьянмарын хув дотор 99 сая жилийн турш хадгалагдсан бичил гүрвэлийн олдвор нь эртний эр гүрвэлийн анатомийн бүтцийг судлах ховор боломжийг эрдэмтдэд олгожээ.
Сам Хьюстон мужийн их сургуулийн судлаач Хуан Дазагаар удирдуулсан баг Мьянмарын Качин мужаас олдсон Carinasquama rusmithii хэмээх шинэ зүйлийн гүрвэлийг судалсан байна. Цэрдийн галавын дунд үед амьдарч байсан энэхүү бяцхан амьтан нь 1.6-2.2 сантиметр урттай бөгөөд орчин үеийн хамгийн жижиг гекко гүрвэлүүдтэй ижил хэмжээтэй байжээ.
Судлаачид микро-CT сканнер ашиглан хув доторх олдворыг гурван хэмжээстээр дүрсэлсэн байна. Сканнераар амьтны биеийн ихэнх хэсэг алга болж, хоосон орон зай үлдсэн ч арьс, хайрсны бүтэц, сүүлний суурь хэсэгт байрлах хаван тод харагджээ. Энэхүү хаван нь эр гүрвэл, могойн нөхөн үржихүйн эрхтэн болох “hemipenal bulge”-тэй тохирч байгааг тогтоосон нь уг олдворыг эрэгчин болохыг батлах гол баримт болсон байна.
Ихэнх чулуужсан олдворуудад зөөлөн эд эсүүд устаж үгүй болдог тул эртний амьтны хүйсийг тогтоох нь маш хэцүү байдаг. Swiss Journal of Palaeontology сэтгүүлд нийтлэгдсэн энэхүү судалгаа нь эртний амьтдын нөхөн үржихүйн онцлогийг хувны ачаар ийнхүү тодорхойлох боломжтойг харуулсан юм. Одоогоор уг гүрвэлийг гекко болон тэдний төрөл төрөгсдийг багтаадаг Pan-Gekkota бүлэгт хамааруулж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A tiny gecko trapped in Myanmar amber for almost 99 million years has given scientists a rare look at one of the oldest known male lizards. The fossil of Carinasquama rusmithii preserves a small tail swelling that may reveal the presence of ancient male reproductive organs.
The new species comes from two pieces of Kachin amber found in Myanmar’s Kachin province. Living during the mid-Cretaceous period, this small reptile measured only 1.6 to 2.2 centimeters in snout-to-vent length, making it similar in size to some of the smallest geckos alive today.
The discovery is unusual because fossils rarely preserve details that can show whether an ancient animal was male or female. In this case, researchers found a clue hidden in the tail. A team led by Juan Daza from Sam Houston State University identified a swelling that matches the appearance of a hemipenal bulge, a feature linked to the paired reproductive organs of male lizards and snakes.
A Tiny Tail Swelling Reveals A Hidden Detail
The study describing Carinasquama rusmithii was published online in the Swiss Journal of Palaeontology. What makes Carinasquama rusmithii interesting is not its tiny size, but the unusual feature preserved near the base of its tail. Researchers believe the swelling corresponds to a hemipenal bulge, an external sign of hemipenes, the paired reproductive organs found in male squamates.
In modern lizards and snakes, these organs are stored inside the tail and are normally difficult to detect from fossil remains. Soft tissues almost always disappear during fossilization, leaving scientists with only bones and other hard structures to study.
The researchers described this fossil as one of the oldest lizard specimens that can be identified as male with strong confidence. Finding the sex of extinct animals is often complicated because many of the features that separate males and females do not survive over millions of years. Usually, they rely on differences in skeletons, body features, or comparisons between several fossils.
“Sex can sometimes be estimated when embryos or eggs are found within a female specimen or associated with the specimen, although other sex-specific traits are rarely preserved in fossils,” explained the authors.
Amber Preserves Details that Fossils Usually Lose
To examine the specimens, the researchers used micro-CT scans to build three-dimensional images of the fossils. The scans showed that the original body had mostly disappeared, leaving a hollow space inside the amber.
The outside of the animal, though, remained surprisingly detailed. The researchers could still observe impressions of scales, skin texture, and the shape of the cloaca.
The study authors reported that the newly found specimen shares several traits with modern gekkotans, including small granular head scales, fused eyelids, similar-sized body scales, and visible skin between the scales.
This type of preservation is one reason amber fossils are so valuable. Unlike many fossils found in rock, amber can sometimes capture delicate structures that would normally vanish before fossilization.
An Ancient Gecko With An Uncertain Family Tree
While the fossil reveals new information about early geckos, scientists are still unsure exactly where Carinasquama rusmithii belongs on the gecko family tree.
The researchers have provisionally placed the species within Pan-Gekkota, a broader group that includes geckos and their close relatives. The study team also noted that:
“This hemipenal bulge in one of the fossils documents the presence of hemipenes in the Squamata, during the mid-Cretaceous, although their origin was probably much earlier likely with the origin of the group.”
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